Magnetic mine



JEANPIERRE TERRIOUX MAGNETIC MINE Filed July 13, 1964 May 24, 1966 Inven+or JEAN- PIERRE' TERR BY KOULULBAQ Mi'omevs United States Patent 3,252,418 MAGNETIC MINE Jean-Pierre Terrioux, Montelimar, France, assignor to Societe anouyme dite: C.R.I.F. (Centre de Recherches Industrielles et de Fabrications) Filed July 13, 1964, Ser. No. 381,955 c Claims priority, application France, July 22, 1963, 942,237; June 22, 1964, 979,179 Claims. (Cl; 102-19.2)

It is now conventional practice to construct mines having a so-called shaped charge, comprising a shaped charge liner positioned above this so as to constitute a projectile which, after the detonation, is projected at high speed against the armor which it is intended to penetrate.

These mines are customarily detonated by a magnetic fuse controlled by a coil which has the disadvantage of being bulky and of considerably increasing the weight of the mine.

The present invention consists essentially in eliminating the shaped charge liner as such from these mines and substituting for it the coil which serves as the fuse for detonating the charge. This coil or coils serves both its normal electrical purpose and that of a projectile, as soon as the mine has been detonated.

Another object of this invention is to provide a new method of manufacturing the coil of such a mine, essentially characterized by the fact that the copper wire from which the coil is formed is covered with a lead coating, for example by passing it through a bath of molten lead, after a light timing to facilitate its adherence. The lead is then superficially oxidized, for example by heating in an oxidizing atmosphere, and the wire which has been treated in this manner is then insulated by applying to it a coating of a thermoplastic varnish. The Wire is then coiled up to form the desired dish, but thicker than its final thickness. The coil is finally heated to plasticiz/e the insulating coating and compressed to the desired thickness.

In order that the object of the invention may be more clearly understood, one embodiment thereof will now be described, purely by way of example, with reference to the single figure of the accompanying drawing.

Turning now to this figure, it will be seen that reference numeral 1 designates the casing of the improved mine according to the present invention, which casing houses a detonator 2 connected to a fuse 3 which functions magnetically in a conventional manner, for example upon the approach of an armored vehicle.

As has already been indicated, in accordance with the essential characteristic of the invention, the coil 5 which is required to explode the mine, replaces the shaped charge liner and for this purpose is mounted in the upper part of the casing 1 above the conventional charge 4. The end wires 5a-5b pass through the central portion of the charge 4 and end at the terminals 6 of the fuse 3. t

It should be noted that the coil 5, whether single or multiple, may be of tightly coiled wire, kept rigid by impregnation or some other process. This wire is preferably made of copper since that metal imparts to the plate the density and melting point which are necessary if the mine is to function properly.

However in order to improve the effectiveness of the mine it is preferable to increase the density of the coil by the following process which forms part of the invention:

It is always assumed that the coil must have the customary shape of a circular dish bounded on its convex and concave faces by conical surfaces, and that in order to serve its electrical purpose the coil must be made of a relatively large number of turns of electrical wire having a diameter of about .15 mm., for example.

In this case one starts with a drawn wire made of pure electrolytic copper, 0.15 mm. in diameter, which is lightly coated by passing it through a bath of molten tin. It is then passed through a bath of molten lead which it leaves with a double coating and a diameter of about 0.18 mm.

The layer of lead is then superficially oxidized by. heating the wire in an oxidizing atmosphere, either continuously or in coils. The oxidized wire is then insulated by covering it with a coating of thermoplastic varnish.

The resulting wire is coiled into the desired shape, but slightly thicker than the intended end product. This coil is then heated to the necessary temperature, so as to partially fuse the thermoplastic varnish and com pressed between a punch and die having the shape of the desired end product until it is reduced to the desired thickness.

In this way the lead layer is caused by the tinning to adhere well to the copper and the thermoplastic layer is caused to adhere well to the lead because it is gripped in the superficial oxide layer. During the compression step any openings which may have been formed during the fusing of the coil are eliminated and the individual turns are brought closer together so that they are stuck tight to each other by the layer of thermoplastic varnish which fills the interstices between the turns of the coil and enlarges the adhesive surface. This adhesion is moreover improved by the cohesion between the various layers making up the wire. The result is a rigid shaped charge liner, which is solid and substantially free from holes.

On the other hand, this shaped charge liner has a much higher density than when it is made by simply coiling up an ordinary copper wire in the presence of lead. This increase in density is important in enabling the shaped charge liner to carry out the ballistic function which it serves in addition to acting as part of the casing for the charge. Moreover, the layer of lead oxide which surrounds each wire and which remains unaffected by the fusion of the thermoplastic varnish, has an insulating power suificiently substantial to supplement that of the varnish and help prevent short circuits between the turns of the coil.

To sum up, it will be seen that the casing for the shaped charge made in this manner comprises on the one hand copper wire which serves primarily to conduct current, but makes a substantial contribution to the weight of the casing for ballistic purposes. 0n the other hand, the tin serves to improve the adherence of the layer of lead which serves primarily to increase the weight of the ballistic charge, but also conducts a little electric current. There is also a layer of lead oxide which has a ballistic function due to its density, a mechanical function in that it improves the adherence of the layer of varnish, and an electrical function in that it provides insulation between the individual turns of the coil. Finally, the layer of thermoplastic varnish serves to stick the assembly together as well as to provide insulation between the coils.

Finally, the shaped charge mine according to the invention has the customary characteristics of such mines, but an improved performance.

It will of course be appreciated that the embodiment of the invention which has just been described has been given purely by way of example and may be modified as to detail without thereby departing from the basic principles of the invention as defined by the following claims.

What is claimed is:

1. A magnetically detonated explosive mine of the type comprising a charge, a detonator, and means comprising an electrical coil for firing said detonator, the turns of said coil being formed into a solid shaped charge liner having a central depression and constituting part of a casing enclosing said charge.

2. A magnetically detonated explosive mine of the type comprising a charge, a detonator, and means comprising an electrical coil for firing said detonator, said coil comprising Wire covered by a coating of thermoplastic insulating material fused to form with said wire a solid shaped charge liner having a central depression and constituting part of a casing enclosing said charge.

3. A mine as claimed in claim 2 in which said wire is covered with successive coatings of tin, lead, and thermoplastic insulating material.

4. A magnetically detonated explosive mine of the type comprising a charge, a detonator, and means comprising an electrical coil for firing said deton ator, said charge being formed with a depression in one side thereof, while said coil fits into said depression and forms part of a casing enclosing said charge.

References Cited by the Examiner UNITED STATES PATENTS 9/1961 Boykin 102-l9.2 X

BENJAMIN A. BORCHELT, Primary Examiner.

V. R. PENDEGRASS, Assistant Examiner. 

1. A MAGNETICALLY DETONATED EXPLOSIVE MINE OF THE TYPE COMPRISING A CHARGE, A DETONATOR, AND MEANS COMPRISING AN ELECTRICAL COIL FOR FIRING SAID DETONATOR, THE TURNS OF SAID COIL BEING FORMED INTO A SOLID SHAPED CHARGE LINER HAVING A CENTRAL DEPRESSION AND CONSTITUTING PART OF A CASING ENCLOSING SAID CHARGE. 